JP2000040916A - Polarization diversity antenna system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To receive radio waves, while avoiding the effect of current flowing though a circuit board by providing a 2nd antenna at a position where currents flowing to a conductive substrate cancel each other. SOLUTION: A whip antenna 2 is provided at an edge part of a circuit board 1. A built-in antenna 3 is provided around the center of the board 1 in a lateral direction and is provided linear symmetrically, with respect to the center axis in the short side direction of the board 1. The whip antenna 2 extends vertically and receives vertically polarized waves. The built-in antenna 3 extends horizontally and receives horizontally polarized waves. The antenna 3 divides a current, that flows to the board 1, into two parts. That is, a 1st part current and a 2nd part current flow in the opposite directions from each other. As a result, the effect of the 1st part current on the antenna 3 and the effect of the 2nd part current on the antenna 3 cancel each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna system used for a mobile communication terminal such as a portable telephone or a pager, and more particularly to a polarization diversity antenna system.

[0002]

2. Description of the Related Art Conventionally, a space diversity antenna system has been used in a radio communication system such as a mobile radio communication system, for example, to improve the reception characteristics of a receiver under fading. . As is well known, the space diversity scheme includes a plurality of antennas. A typical space diversity antenna system for a mobile phone includes, for example, a whip antenna protruding from the body of the mobile phone and a built-in antenna for space diversity. Since the base station that controls the mobile phone communicates with the mobile phone using vertical polarization, the two antennas are positioned to receive vertical polarization. In particular, the built-in antenna is provided on the top of the main body so as to receive radio waves without being interrupted by the user of the mobile phone.

FIG. 1 shows a conventional space diversity system.
FIG. 2 schematically illustrates an antenna system. This antenna system is used, for example, in the 800 MHz band. In FIG. 1, the space diversity antenna system includes a circuit board 10, a whip antenna 20, and a built-in antenna 30. An integrated circuit and electronic components are mounted on the circuit board 10.
Installed inside the body of the mobile phone. The whip antenna 20 is provided vertically on the upper part of the main body, that is, in the Z direction. The built-in antenna 30 is mounted on an upper part of the circuit board 10. The built-in antenna 30 has an inverted F shape in order to reduce the space for mounting.
In the figure, the built-in antenna 30 is shown in an enlarged manner within a dotted circle in the figure. Here, for example, the length of the whip antenna 20 is 90 mm. The height of the main body of the mobile phone is 120 mm, and its width is 35 mm.
This width is determined by the wavelength of the radio wave. Further, the height, width, and depth of the built-in antenna 30 are 5 mm, respectively.
35 mm and 20 mm.

FIG. 2 shows the characteristics of the conventional space diversity antenna system shown in FIG.
2 shows a radiation pattern of the built-in antenna 30, and FIG.
(B) shows the whip antenna 20 in the YZ plane of FIG.
3 shows the radiation pattern of As shown in FIG. 2, the built-in antenna 30 and the whip antenna 20 have a characteristic that the θ component radiates strongly in the horizontal direction, that is, the Y direction, while the φ component radiates weakly in the horizontal direction. here,
Since the transmitting antenna system and the receiving antenna system are reversible, "radiating" and "receiving" are equivalent. That is, in FIG. 2, both the built-in antenna 30 and the whip antenna 20 have strong directivity to vertical polarization in the Y direction.

[0005] However, the conventional space diversity.
In the antenna system, since the built-in antenna 30 is close to the whip antenna 20, these two antennas could not sufficiently provide the effect of space diversity. The two antennas at such positions deteriorate the characteristics of the other antenna due to electromagnetic coupling between the two antennas.

[0006]

On the other hand, similarly to the space diversity antenna system, a polarization diversity antenna system is known. In a polarization diversity antenna system, the built-in antenna 30
Is required to receive a polarization having a different direction from the polarization received by the whip antenna 20, that is, a horizontal polarization. However, since the body of the mobile phone is small and cannot be provided with a large circuit board or a large grounding plate for grounding, a large current flows through the grounding plate due to the vertical polarization received by the grounding plate. Therefore, the characteristics of the built-in antenna 30 are determined by the high-frequency current flowing through the ground plate more vertically than the high-frequency current flowing through the built-in antenna 30 itself. That is, the current flowing through the ground plate prevents the built-in antenna 30 from receiving the horizontally polarized wave.

FIG. 3 schematically illustrates a polarization diversity antenna system with a built-in antenna placed horizontally, and FIG. 4 shows the characteristics of the built-in antenna. Although the built-in antenna 30 is installed horizontally, as shown in FIG. 4, the angle θ is substantially similar to the characteristic shown in FIG.
The component radiates strongly in the horizontal direction. The reason why the radiation direction of the built-in antenna 30 does not change is that the built-in antenna 30 mainly depends on a high-frequency current flowing perpendicularly to the circuit board 10. As a result, the polarization diversity antenna system configured as shown in FIG. 3 could not provide the effect of the polarization diversity.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a polarization diversity antenna system which overcomes the disadvantages of the prior art. According to the first invention, a polarization diversity antenna system includes a first antenna that receives a first polarization and a second antenna that receives a second polarization perpendicular to the first polarization. An antenna, and a conductive substrate provided with a second antenna, wherein the second antenna has a first antenna
The current flowing through the conductive substrate by receiving either one of the first and second polarizations is provided at a position where they cancel each other.

[0009] In the polarization diversity antenna system according to the first aspect of the present invention, it is preferable that the second antenna is provided symmetrically with respect to a central axis in a lateral direction of the conductive substrate. Polarization diversity antenna according to the first invention
In the system, it is preferable that the first antenna is provided symmetrically with respect to the central axis in the lateral direction of the conductive substrate. In the polarization diversity antenna system according to the first invention, it is preferable that the second antenna is a built-in antenna, an inverted F antenna, an M-type antenna, an inverted L antenna, or a loop antenna.

According to the second invention, the polarization diversity
The antenna system includes a second antenna having a first antenna element and a second antenna element, wherein the first antenna element and the second antenna element
The element is provided symmetrically with respect to the central axis in the lateral direction of the conductive substrate. In the second polarization diversity antenna system, it is preferable that the first antenna element and the second antenna element have substantially the same shape. The second polarization diversity antenna system is such that the second antenna is a built-in antenna,
Desirably, it is an inverted F antenna, an inverted L antenna, an M-shaped antenna, or a loop antenna.

According to the third invention, the polarization diversity
An antenna system is provided with an antenna having a first antenna element and a second antenna element for selectively receiving either a first polarization or a second polarization, and an antenna. A conductive substrate, wherein the first antenna element and the second antenna element are symmetrically arranged about a central axis of the conductive substrate. A third polarization diversity antenna system is:
It is desirable that the first antenna element and the second antenna element are arranged symmetrically with respect to the central axis in the lateral direction of the conductive substrate.

According to a fourth aspect of the present invention, a polarization diversity antenna system for a mobile phone is provided with a whip antenna for receiving vertically polarized waves, a built-in antenna for receiving horizontally polarized waves, and a built-in antenna. The built-in antenna is provided at a position where a current generated when the conductive substrate receives one of vertical polarization and horizontal polarization, and a current flowing through the conductive substrate cancels each other. Can be

According to a fifth aspect of the present invention, a polarization diversity antenna system for a mobile phone is provided with a whip antenna for receiving vertically polarized waves, a built-in antenna for receiving horizontally polarized waves, and a built-in antenna. The built-in antenna is provided symmetrically with respect to the central axis in the lateral direction of the conductive substrate.

According to a sixth aspect, a mobile phone includes a whip antenna for receiving vertically polarized waves, a built-in antenna for receiving horizontally polarized waves, and a conductive substrate on which the built-in antenna is provided. A receiving circuit that receives either the polarized wave or the horizontally polarized wave, and a switch circuit that selectively supplies one of the vertically polarized wave received by the whip antenna and the horizontally polarized wave received by the built-in antenna to the receiving circuit. The built-in antenna is provided at a position where a current generated when the conductive substrate receives one of vertical polarization and horizontal polarization and which flows through the conductive substrate cancels each other.

According to the seventh invention, the portable telephone comprises a whip antenna for receiving vertically polarized waves, a built-in antenna for receiving horizontally polarized waves, a conductive substrate provided with the built-in antenna, and a vertically polarized wave. And a receiving circuit for receiving either the horizontal polarization or the vertical polarization, and a switch circuit for selectively supplying the reception circuit with either the vertical polarization received by the whip antenna or the horizontal polarization received by the built-in antenna. The built-in antenna is provided symmetrically with respect to the central axis in the lateral direction of the conductive substrate. The above summary of the present invention does not list all of the necessary features of the present invention, and sub-combinations of these features may also constitute the present invention.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION <Specific Example 1> The present invention will be described below with reference to embodiments of the present invention. Not all combinations of the features described are necessarily essential to the solution of the invention.

The polarization diversity antenna of the first embodiment
The system will be described. The main feature of the specific example 1 is that the built-in antenna is provided at the center in the longitudinal direction of the circuit board, that is, in the horizontal direction. As a result, the current flowing between the upper end of the circuit board and the built-in antenna and the current flowing between the lower end of the circuit board and the built-in antenna cancel each other, so that the current flowing through the circuit board affects the characteristics of the built-in antenna. The effect can be reduced or eliminated.

FIG. 5 shows a polarization diversity antenna system of the first embodiment, and FIG. 6 shows a radiation pattern of the built-in antenna. As shown in FIG. 5, the polarization diversity antenna system includes a circuit board 1, a whip
An antenna 2 and a built-in antenna 3 are provided. The circuit board 1
It has wirings for passing current through the integrated circuit, the electronic components, and the circuit board 1. The whip antenna 2 is a circuit board 1
The built-in antenna 3 is provided in the vicinity of the center of the circuit board 1 in the lateral direction. That is, the circuit board 1 is provided symmetrically with respect to the central axis in the lateral direction. Since the whip antenna 2 extends in the vertical direction, it receives vertically polarized waves. In contrast, the built-in antenna 3 receives horizontal polarization because it extends in the horizontal direction.

The built-in antenna 3 divides the current flowing through the circuit board 1 into two parts. Specifically, the electric wave received by the circuit board 1 causes the circuit board 1 to generate a current. However, since the built-in antenna 3 is provided in the vicinity of the center of the circuit board 1, its current is divided into two parts, that is, the first part.
And a second part. The current of the first portion and the current of the second portion flow in opposite directions.
As a result, the influence of the current of the first part on the built-in antenna 3 and the influence of the current of the second part on the built-in antenna 3 cancel each other. As shown in FIG.
The components radiate very strongly in the horizontal direction, i.e. in the Y direction, which will differ from the conventional radiation pattern of FIG. In summary, as shown in FIG.
Whip antenna 2 receives vertical polarization in the Y direction,
On the other hand, as shown in FIG. 6, the built-in antenna 3 receives a horizontally polarized wave in the Y direction. In addition, whip antenna 2
Does not receive radio waves in the Z direction, but the built-in antenna 3
Radio waves are received in the Z direction.

FIG. 7 is a diagram for explaining the mounting position of the built-in antenna on the circuit board, and the length L indicates the mounting position of the built-in antenna. FIG. 8 shows the radiation pattern,
8A shows a radiation pattern when the length L is 10 mm, FIG. 8B shows a radiation pattern when the length L is 20 mm, and FIG. L is 30
4 shows the radiation pattern when mm. Similarly, FIG.
Indicates a radiation pattern when the length L is 0 mm,
FIG. 4 shows a radiation pattern when the length L is 40 mm. Here, the length L represents the distance between the center of the circuit board 1 and the position of the built-in antenna 3. As shown in these radiation patterns, the longer the length L, the more the built-in antenna 3 radiates in the same manner as the whip antenna 2. That is, since the current flowing through the circuit board 1 increases with the length L, the characteristics of the built-in antenna 3 deteriorate as a polarization antenna. As a result, the built-in antenna 3 is
When it is separated from the center of the circuit board 1 by a length of 15% or less of the length in the longitudinal direction, the polarization diversity antenna
A great effect can be given as a system.

In the above embodiment, the built-in antenna 3, that is, the inverted F antenna is used as the built-in antenna. But,
It is also possible to use loop antennas, inverted L antennas, and improved versions of those antennas as built-in antennas. Further, the whip antenna 2 at the end of the circuit board 1
Alternatively, an antenna functioning as the whip antenna 2 can be provided at the upper end or the lower end of the circuit board 1.

As described above, according to the first embodiment, the built-in antenna 3 used for polarization diversity together with the whip antenna 2 is located at the center of the circuit board 1, more precisely, at the center of the circuit board 1. Since the internal antenna 3 is provided symmetrically with respect to the line, the built-in antenna 3
Divided into two parts. As a result, the effects of the currents of these two parts on the built-in antenna 3 are reduced or canceled out, and the built-in antenna 3 can function as a polarization diversity antenna that receives vertically polarized waves.

<Specific Example 2> A polarization diversity antenna system according to a specific example 2 will be described below. FIG. 9 schematically illustrates a polarization diversity antenna system according to the second embodiment. As shown, in contrast to Example 1 in which the whip antenna 2 is provided at the end of the circuit board 1, the whip antenna 2 'functioning as a whip antenna is provided in the circuit board 1. . More specifically,
It is provided along the longitudinal direction of the circuit board 1, that is, vertically, and is symmetric about the center line of the circuit board 1. As a result, the whip antenna 2 'and the built-in antenna 3 are at right angles to each other.

As described above, according to the second embodiment, unlike the first embodiment, the whip antenna 2 ′ functioning as a whip antenna is provided vertically in the circuit board 1, ie, 1 are provided vertically along the longitudinal direction and symmetrically about the horizontal center line of the circuit board 1. Therefore, in the specific example 2, in addition to the effect similar to the effect of the specific example 1, the size of the polarization diversity antenna system can be smaller than that of the specific example 1.

<Third Embodiment> The polarization diversity antenna system of the third embodiment will be described below. FIG. 10 schematically shows the configuration of the third embodiment. As shown, the built-in antenna 3 includes a first built-in antenna element 3a and a second built-in antenna element 3b. The first built-in antenna element 3a is placed horizontally on top of the circuit board 1 so that the built-in antenna 3 receives a polarization having a different direction from the polarization received by the whip antenna 2. , The second built-in antenna element 3b
Are placed horizontally below the circuit board 1. More specifically, the built-in antenna 3 includes a first built-in antenna
Element 3a and second built-in antenna element 3b
When both are powered, ie, function, they can receive such polarizations. FIG. 11 shows a radiation pattern of the built-in antenna of FIG.

When receiving the horizontally polarized wave, the circuit board 1 is the circuit board 1 and the first built-in antenna element 3
a and a current flows through the portion divided by the second built-in antenna element 3b. Since this current cancels each other, the first built-in antenna element 3a
And the second built-in antenna element 3b are both immune to this current. As shown in FIG. 11, the radiation characteristic of the built-in antenna 3 is similar to the radiation characteristic of the specific example 1 shown in FIG. 6, and is suitable for a polarization diversity antenna system.

As described above, the first and second built-in antenna elements 3a and 3b are located above and below the circuit board 1, respectively. Further, it is desirable that the first and second built-in antenna elements 3a and 3b are provided at equal distances from the center line of the circuit board 1. That is, the first and second built-in antenna elements 3a, 3b
Are desirably provided symmetrically about a horizontal center line of the circuit board 1 so that currents flowing through the circuit board 1 cancel each other. Further, it is desirable that the first and second built-in antenna elements 3a and 3b have the same shape so as to have the same radiation characteristics.

As described above, according to the specific example 3, the first
The built-in antenna 3 including the built-in antenna element 3a and the second built-in antenna element 3b can provide a greater polarization diversity effect than the conventional technology.

<Example 4> A polarization diversity antenna system according to Example 4 will be described. FIG. 12 shows a specific example 4.
FIG. 13A shows two internal antennas.
FIG. 13 shows the radiation pattern of one of the elements,
(B) shows a radiation pattern combining two built-in antenna elements. As shown in FIG. 12, the polarization diversity antenna system of the fourth embodiment does not include a whip antenna. However, built-in antenna 3
Includes two built-in antenna elements 3c and 3d as in the third embodiment. When one of the two built-in antenna elements 3c, 3d is powered, the built-in antenna 3 can receive vertical polarization. Conversely, when both elements 3c, 3d are powered, the built-in antenna 3 can receive horizontal polarization. That is, when one of the two built-in antenna elements 3c and 3d receives a polarized wave, a large current flows through the circuit board 1. As a result, as shown in FIG.
Since the θ component radiates strongly while the φ component radiates weakly like the conventional built-in antenna 30 shown in FIG.
It is suitable for receiving vertically polarized waves. Conversely, when both of the two built-in antenna elements 3c and 3d receive polarized waves, as shown in FIG.
While it radiates strongly, the φ component also radiates strongly like the radiation pattern of the built-in antenna in the specific example 1 of FIG. 6, so that it is suitable for receiving horizontally polarized waves.

As described above, according to Embodiment 4, the built-in antenna 3 includes two built-in antenna elements 3c,
3d and can receive vertical polarization by using one of the two antenna elements, and can receive horizontal polarization by using both. .

FIG. 14 shows an example of an antenna functioning as the built-in antenna 3. The feed point 3f is used to feed each antenna, and the short point 3s is used to establish a short circuit. In the above specific example, a planar inverted F antenna is used as the built-in antenna 3. However, as shown in FIG.
An inverted L antenna, M-shaped antenna, loop antenna, or a modified version of those antennas can be used.
Symmetric to the shape of the planar inverted-F antenna, they are all rod-shaped. The planar inverted-F antenna is an improved version of the inverted-F antenna shown in FIG. 14B, but all of the antennas in FIG. 14 can provide the above-described effects.

As shown in FIG. 15, the polarization diversity antenna system functions well in a portable telephone or a PHS in which the space for the circuit board 1 is small. In the figure, the mobile phone 4 includes a whip antenna 2, a built-in antenna 3,
A switch 5 and a receiving circuit 6 are provided. Switch 5
A current generated in the whip antenna 2 or a current flowing in the built-in antenna 3 is selected, and the selected current is supplied to the receiving circuit 6. As described above, since the current flowing through the built-in antenna 3 can flow without being affected by the current flowing through the circuit board 1, the mobile phone can obtain the effect of the polarization diversity antenna system.

As described above, in the conventional polarization diversity antenna system, as shown in FIG.
The characteristic of the circuit board 10 is that a small current I10 and a large current I20 flow on the circuit board 10 toward the built-in antenna 30. Therefore, regarding the propagation of radio waves, the current I1
Such an imbalance between 0 and I20 changes the characteristics of the built-in antenna 30 so that the built-in antenna 30 cannot emit vertically polarized waves. Since the transmitting and receiving antennas are reversible, such imbalances
Prevents built-in antenna 30 from receiving vertically polarized waves.

In contrast, according to the present invention, since the built-in antenna 3 is provided symmetrically with respect to the center line of the built-in antenna 3, as shown in FIG. Currents I1 and I2 flow. Therefore, the currents I1 and I2 cancel each other. Such cancellation or balance allows the built-in antenna 3 to receive vertically polarized waves.

Similarly, since the built-in antenna elements 3a and 3b of the third embodiment are provided symmetrically with respect to the center line of the built-in antenna 3, as shown in FIG. 18, currents I3, I4 and I5 , And I6 flow. That is,
The currents I3 and I6 cancel each other and the current I3
4, I5 cancel each other out. Such cancellation also enables the built-in antenna 3 to receive vertically polarized waves.

Although the present invention has been described with reference to the embodiment, the technical scope of the present invention is not limited to the scope described in the above embodiment. It is apparent to those skilled in the art that various changes or improvements can be added to the above embodiment. It is apparent from the description of the appended claims that embodiments with such changes or improvements can be included in the technical scope of the present invention.

[0037]

As is apparent from the above description, according to the polarization diversity antenna system of the present invention, the antenna for polarization diversity receives radio waves while avoiding the influence of the current flowing through the circuit board. Can be.

[Brief description of the drawings]

FIG. 1 shows a configuration of a conventional space diversity antenna system.

FIG. 2 shows a radiation pattern of a built-in antenna of a conventional space diversity antenna system and a whip antenna.
3 shows a radiation pattern of an antenna.

FIG. 3 shows a configuration of a conventional polarization diversity antenna system.

FIG. 4 shows a radiation pattern of the polarization diversity antenna system of FIG.

FIG. 5 shows a configuration of a polarization diversity antenna system of Example 1.

FIG. 6 shows a radiation pattern of the built-in antenna according to the first embodiment.

FIG. 7 shows the specification of the position of the built-in antenna of the first embodiment.

FIG. 8 shows lengths (L) indicating the distance between the center of the circuit board and the position of the built-in antenna, which are 10 mm and 20 m, respectively.
5 shows a radiation pattern of the built-in antenna of the specific example 1 when m and 30 mm.

FIG. 9 shows a configuration of a polarization diversity antenna system of a specific example 2.

FIG. 10 shows a configuration of a polarization diversity antenna system of Example 3.

FIG. 11 shows a radiation pattern of the built-in antenna according to the third embodiment.

FIG. 12 shows a configuration of a polarization diversity antenna system of a fourth embodiment.

FIG. 13 shows a radiation pattern of one of the two built-in antenna elements of the fourth embodiment and a radiation pattern of a combination of the two built-in antenna elements of the fourth embodiment.

FIG. 14 shows a configuration of an inverted L antenna, a configuration of an inverted F antenna,
1 shows a configuration of an M-type antenna and a configuration of a loop antenna.

FIG. 15 shows a configuration of a mobile phone on which the polarization diversity antenna system of the present invention is mounted.

FIG. 16 shows a current flowing through a circuit board of a conventional polarization diversity antenna system.

FIG. 17 shows a current flowing through the circuit board of the polarization diversity antenna system of the first embodiment.

FIG. 18 shows a current flowing through the circuit board of the polarization diversity antenna system of the third embodiment.

[Explanation of symbols]

 1 circuit board 2 whip antenna 3 built-in antenna

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // H01Q 3/24 H01Q 3/24 (72) Inventor Hirotaka Saito 3-14-20 Higashinakano, Nakano-ku, Tokyo (72) Inventor Kinami Sasaki 3-14-20 Higashinakano, Nakano-ku, Tokyo International Electric Company, Ltd.

Claims (20)

[Claims] 1. A first antenna for receiving a first polarization, a second antenna for receiving a second polarization perpendicular to the first polarization, and the second antenna are provided. The second antenna is located at a position where currents flowing through the conductive substrate by receiving one of the first polarized wave and the second polarized wave cancel each other. A polarization diversity antenna system, which is provided. 2. The polarization diversity antenna system according to claim 1, wherein the second antenna is provided symmetrically with respect to a short-side center axis of the conductive substrate. Polarization diversity antenna system. 3. The polarization diversity antenna system according to claim 1, wherein the first antenna is provided symmetrically with respect to a short-side center axis of the conductive substrate. Polarization diversity antenna system. 4. The polarization diversity antenna system according to claim 1, wherein the second antenna is a built-in antenna. 5. The polarization diversity antenna system according to claim 1, wherein the second antenna is an inverted-F antenna. 6. The polarization diversity antenna system according to claim 1, wherein the second antenna is an inverted L antenna. 7. The polarization diversity antenna system according to claim 1, wherein the second antenna is a loop antenna. 8. The polarization diversity antenna system according to claim 1, wherein the second antenna has a first antenna element and a second antenna element, and wherein the first antenna has a first antenna element and a second antenna element. A polarization diversity antenna system, wherein the antenna element and the second antenna element are provided symmetrically with respect to a central axis in a lateral direction of the conductive substrate. 9. The polarization diversity antenna system according to claim 8, wherein the first antenna element and the second antenna element have substantially the same shape. Polarization diversity antenna system. 10. The polarization diversity antenna system according to claim 8, wherein the second antenna is a built-in antenna. 11. The polarization diversity antenna system according to claim 8, wherein the second antenna is an inverted F antenna. 12. The polarization diversity antenna system according to claim 8, wherein the second antenna is an inverted L antenna. 13. The polarization diversity antenna system according to claim 8, wherein the second antenna is an M-type antenna. 14. The polarization diversity antenna system according to claim 8, wherein the second antenna is a loop antenna. 15. An antenna having a first antenna element and a second antenna element for selectively receiving one of a first polarization and a second polarization, and the antenna provided with the antenna. A polarization substrate, wherein the first antenna element and the second antenna element are symmetrically arranged with respect to a center axis of the conductive substrate.
Antenna system. 16. The polarization diversity according to claim 15,
An antenna system, comprising: the first antenna element and the second antenna
The polarization diversity antenna system, wherein the elements are symmetrically arranged with respect to a central axis in a lateral direction of the conductive substrate. 17. A polarization diversity antenna system for a mobile phone, comprising: a whip antenna for receiving a vertically polarized wave, a built-in antenna for receiving a horizontally polarized wave, and a conductive antenna provided with the built-in antenna. A substrate, wherein the built-in antenna is a current generated when the conductive substrate receives one of the vertical polarization and the horizontal polarization, and the current flowing through the conductive substrate cancels each other. 1. A polarization diversity antenna system, comprising: 18. A polarization diversity antenna system for a mobile phone, comprising: a whip antenna for receiving a vertically polarized wave, a built-in antenna for receiving a horizontally polarized wave, and a conductive antenna provided with the built-in antenna. A polarization diversity antenna system, comprising: a substrate; and wherein the built-in antenna is provided symmetrically with respect to a central axis in a lateral direction of the conductive substrate. 19. A whip antenna for receiving a vertically polarized wave, a built-in antenna for receiving a horizontally polarized wave, and a conductive substrate provided with the built-in antenna. A receiving circuit for receiving any of the vertical polarization received by the whip antenna, and a switch circuit for selectively supplying any of the horizontal polarization received by the built-in antenna to the reception circuit, The built-in antenna may be a current generated when the conductive substrate receives any of the vertical polarization and the horizontal polarization, and may be provided at a position where currents flowing through the conductive substrate cancel each other. Features mobile phones. 20. A whip antenna for receiving a vertically polarized wave, a built-in antenna for receiving a horizontally polarized wave, a conductive substrate provided with a built-in antenna, and any one of the vertically polarized wave and the horizontal polarized wave And a switch circuit for selectively supplying any of the vertical polarization received by the whip antenna and the horizontal polarization received by the built-in antenna to the reception circuit. A mobile phone, wherein the antenna is provided symmetrically with respect to a central axis in a lateral direction of the conductive substrate.